Intracellular pathogens can manipulate tyrosine kinase pathways by diverting host signals to control entry of the pathogen into the host cell. A small molecule screen identified a class of molecules called tyrphostins, tyrosine kinase inhibitors, which disrupted the normal process associated with Listeria monocytogenes infection. Tyrphostins are synthetic tyrosine kinase inhibitors, and they have been shown to inhibit growth of viral pathogens as well as partially block parasitic entry into host cells. Many host cell signaling pathways are regulated by tyrosine kinases but little is known about how tyrphostins manipulate host factors during infection. Standard assays carried out in the presence of tyrphostins will further the understanding of processes associated with L. monocytogenes pathogenesis. The goal of this research is to understand the role of tyrosine kinases during L. monocytogenes infection.